Onsite hardness testing of reinforcement

Onsite hardness testing and laboratory based tensile testing was conducted on reinforcement used in pre 1960 bridges. The primary purpose of the testing was to develop a procedure to determine the yield strength of reinforcement insitu using a non destructive test method to improve the estimation of the load carrying capacity of existing bridges. The secondary objective was to collect data on the yield strength of reinforcement to assist in predicting the benefits which may be obtained from onsite hardness testing of bridges. From the test data collected a correlation between the onsite hardness and the yield strength of reinforcement was determined. This empirical correlation may be used to assess onsite the yield strength of reinforcement. The average yield strength of reinforcement tested was found to be approximately 30 per cent higher than the manufacturer's specifications. The results of the tensile testing indicated that assuming a yield strength of 230 MPa is conservative for unidentified reinforcement and that characteristic strengths of up to 285 MPa are possible in pre 1960 bridges. (a) For the covering entry of this conference, please see ITRD abstract no. E211602.